Reinforcing bar-binding machine

ABSTRACT

A reverse rotational number of a binding wire feed mechanism is set such that a binding wire is completely pulled back regardless of a boldness or flexibility of the binding wire, a diameter of a reinforcing bar or the like. A driven gear  14  having a V groove of the binding wire feed mechanism is brought into elastic contact with a main drive gear  13  having a V groove by a spring and the binding wire is fed by pinching the binding wire by the main drive gear  13  having the V groove and the driven gear  14  having the V groove. After feeding out the binding wire to form a loop around the reinforcing bar and clamping a front end of the binding wire by a twist mechanism, the binding wire feed mechanism is rotated reversely and the binding wire is pulled back to be wound around the reinforcing bar. After stopping the binding wire, the main drive gear  13  having the V groove and the driven gear  14  having the V groove are slipped relative to the binding wire to rotate idly and continue to rotate reversely until a predetermined rotational number.

TECHNICAL FIELD

The present invention relates to a reinforcing bar binding machine,particularly relates to a reinforcing bar binding machine constituted toadjust a length of a binding wire by pulling back the binding wire afterwinding the binding wire around a reinforcing bar.

BACKGROUND ART

There is known a reinforcing bar binding machine having a binding wirefeed-mechanism for feeding out a binding wire and hanging the bindingwire around a reinforcing bar and a binding wire twist mechanism fortwisting the binding wire wound around the reinforcing bar to bind forcarrying out binding operation of 1 cycle by successively executingbinding ire binding operation and binding wire twisting operation bytrigger operation. Further, as disclosed in, for example, JP-A-08-034406(claim 2, paragraph No. 0022, paragraph No. 0055), there is proposed areinforcing bar binding machine for pulling back a binding wire afterbinding wire feed operation, bringing a loop of the binding wire intoclose contact with a reinforcing bar to start twisting operation.According to the reinforcing bar binding machine, by pulling back thebinding wire, a line length thereof is adjusted in accordance with adiameter of the reinforcing bar to thereby promote finishing and alsosave to reduce an amount of consuming the binding wire.

In the case of constituting the reinforcing bar binding machine suchthat the binding wire is pulled back after the binding wire feedingoperation and the twisting operation is started in a state of bringingthe binding wire into close contact with the reinforcing bar, setting ofa pull back tension poses a problem. When a feeding force of the bindingline feed mechanism is weak, time is taken in pulling back the bindingwire or the binding wire cannot be pulled back. Further, when thefeeding force is conversely excessively large, there is a concern ofcutting the binding line.

As a means for preventing such a drawback from being brought about, itis conceivable to provide electric control means for setting a motortorque to a degree of being sufficient for pulling back the binding wireand stopping a motor by detecting an increase in a drive current by arapid increase in a pull back resistance in finishing to pull back thebinding wire. However, a flexibility of the binding wire significantlydiffers by a kind of the binding wire or an environmental condition ofan outside air temperature or the like and a width of varying the pullback resistance is wide and therefore, a width of changing the currentis not constant, a peak value of the current in stopping the bindingwire is significantly varied also by a remaining capacity of a powersource battery and therefore, it is difficult to control to stop themotor stably without being influenced by these factors. Further, whenthere is constructed a constitution of setting a threshold value of thecurrent of stopping the motor at each time for pertinently pulling backthe binding wire, the operation becomes complicated and practicalperformance is deteriorated. Further, there also poses a problem thatcost is increased by providing a control circuit including a currentdetecting circuit or the like.

DISCLOSURE OF THE INVENTION

Hence, there poses a technical problem to be resolved in order to stablypull back a binding wire regardless of a kind of the binding wire, andan external condition, a voltage of a battery or the like and it is anobject of the invention to resolve the above-described problem.

The invention is proposed to achieve the above-described object. Thereis provided a reinforcing bar binding machine comprising a binding wirefeed mechanism for feeding out a binding wire to wind around areinforcing bar, a binding wire grasp mechanism of grasping and twistingthe winding wire wound around the reinforcing bar, a binding wire pullback function of pulling back a loop of the binding wire wound aroundthe reinforcing bar to be brought into close contact with thereinforcing bar and thereafter twisting the binding wire, control meansfor reversely rotating a drive system of the binding wire feed mechanismby a constant number in pulling back the binding wire, and means forpermitting to slip the drive system for restricting a pull back tensionexerted to the binding wire to be equal to or smaller than a limit valueof cutting the binding wire.

Further, there is provided the reinforcing bar binding machineconstituting the binding wire feed mechanism by bringing a driven sheaveinto elastic contact with a main drive sheave and constituted such thatwhen a pull back tension exerted to the binding wire pinched between thepair of sheaves exceeds a certain value, the sheaves are idly rotated torestrict the pull back tension exerted to the binding wire.

Further, there is provided the reinforcing bar binding machineconstituting the binding wire feed mechanism by bringing the drivensheave into elastic contact with the main drive sheave, interposing atorque limiter of a friction clutch or a ball clutch to a drive systemof the binding wire feed mechanism and constituted such that when a pullback tension exerted to the binding wire pinched between the pair ofsheaves exceeds a certain value, the main drive sheave and the drivensheave are stopped to restrict the pull back tension exerted to thebinding wire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a reinforcing bar binding machine.

FIG. 2 is a side sectional view of a binding wire feed mechanism.

FIG. 3 is a front view of the binding wire feed mechanism.

FIG. 4 is a bottom view of the binding wire feed mechanism.

FIG. 5 shows a step of operating the reinforcing bar binding machine andis a side view showing an initial state.

FIG. 6 shows a step of operating the reinforcing bar binding machine andis a side view showing a step of forming a loop of the binding wire.

FIG. 7 shows a step of operating the reinforcing bar binding machine andis a side view showing a step of pulling back the binding wire.

FIG. 8 shows a step of operating the reinforcing bar binding machine andis a side view showing a step of twisting the binding wire.

FIG. 9 is an explanatory view of a constitution showing other embodimentof the binding wire feed mechanism.

Further, in notations in the drawings, numeral 1 designates areinforcing bar binding machine, numeral 3 designates a binding wireclamp mechanism, numeral 4 designates a binding wire feed mechanism,numeral 6 designates a magazine, numeral 7 designates a nose, numeral 8designates a center clamp plate, numeral 9 designates a right clampplate, numeral 10 designates a left clamp plate, numeral 11 designates acutter devise, numeral 13 designates a main drive gear having a Vgroove, numeral 14 designates a driven gear having a V groove, numeral15 designates s feed motor, numeral 16 designates a reduction gearmechanism, numeral 17 designates a lever, numeral 18 designates acompression coil spring, numeral 19 designates a binding wire guide,numeral 23 designates a gear for feeding, numeral 24 designates a torquelimiter, notation W designates a binding wire, notation S designates sreinforcing bar.

BEST MODE FOR CARRYING OUT THE INVENTION

Although an embodiment of the invention will be described in details inreference to the drawings as follows, for convenience of explanation,first, an outline of a total constitution of a reinforcing bar bindingmachine will be explained. FIG. 1 shows a reinforcing bar bindingmachine 1. A binding wire clamp mechanism 3 and A binding wire feedmechanism 4 are included in a casing 2. A binding wire reel (notillustrated) is charged into the magazine 6 arranged on a front side ofa grip 5. A binding wire W wound on the binding wire reel is fed out toan upper side by the binding wire feed mechanism 4, forms a loop along aguide groove 7 a at an inner periphery of a nose 7 and is fed into thebinding wire clamp mechanism 3. The binding wire clamp mechanism 3 isconstituted by a center clamp plate 8 and a movable clamp plates 9, 10on left and right sides thereof. A front end of the binding wire W isbrought to between the right clamp plate 9 (depth side of paper face ofFIG. 1) and the center clamp plate 8 to be clamped. Successively, thebinding wire feed mechanism 4 is driven to reversely rotate to pull backthe binding wire W to bring about a state of winding the binding wire Waround the reinforcing bar and the left clamp plate 10 is closed. A rearend of the binding wire loop is clamped by the left clamp plate 10 andthe center clamp plate 8. Further, the cutter devise 11 cuts the rearend of the binding wire loop. The binding wire clamp mechanism 3 isrotated in a state of clamping both ends of the binding wire loop. Bytwisting together the both ends of the binding wire loop, thereinforcing bar is wound.

FIG. 2 through FIG. 4 shows the binding wire feed mechanism 4. A maindrive gear 13 having a V groove and a driven gear 14 having a V grooveare arranged on a base plate 12. The two pieces of the gears 13, 14having the V grooves are brought in mesh with each other. A gear of thereduction gear mechanism 16 connected to the feed motor 15 is brought inmesh with the main drive gear 13 having the V groove. As shown by FIG.3, the driven gear 14 having the V groove which is not directly broughtin mesh with the feed motor 15 is attached to the lever 17 and isbrought into elastic contact with the main drive gear 13 having the Vgroove by a spring force of the compression coil spring 18 attached tothe lever 17, and a contact pressure between the main drive gear 13having the V groove and the driven gear 14 having the V groove isdetermined by the spring force of the compression coil spring 18.

When a lower end portion of the lever 17 is pressed to a center side(left side of FIG. 3), the driven gear 14 having the V groove attachedto an upper portion thereof is moved laterally to leave from the maindrive gear 13 having the V groove on the motor side, and the bindingwire can be passed between the main drive gear 13 having the V grooveand the driven gear 14 having the V groove. The binding wire guide 19having a funnel shape is provided on a lower side of a middle of the twopieces of the gears 13, 14 having the V grooves, and the binding wire isset to between the main drive gear 13 having the V groove and the drivengear 134 having the V groove by passing the binding wire through thebinding wire guide 19 from the lower side.

As described above, in 1 cycle operation of the reinforcing bar bindingmachine 1, respective steps of feeding the biding wire, clamping thefront end of the binding wire loop, pulling back the binding wire,clamping the rear end of the binding wire loop, cutting the binding wireand twisting the binding wire are successively executed by a control ofa control portion of a microprocessor or the like. The aspect of theinvention resides numbers of reversely rotating the feed motor 15 andthe main drive gear 13 having the V groove of the binding wire feedmechanism 4, in the step of pulling back the binding wire, are set tovalues sufficient for completely pulling back the binding wire, in anyconditions. Further, a principal point thereof resides in that thecontrol pressure of the main drive gear 13 having the V groove and thedriven gear 14 having the V groove is set in consideration of a strengthof the binding wire. When two pieces of the gears 13, 14 having the Vgrooves are rotated in a state of forcibly stopping the binding wire,the binding wire is prevented from being cut by slipping the gears 13,14 having the V grooves and the biding wire.

FIG. 5 shows an initial state of the reinforcing bar binding machine 1,and a front end of the binding wire W is disposed at a position the sameas that of a front end of the cutter devise 11. When a guide plate 21hung between the nose 7 and a lower side guide arm 20 of the reinforcingbar binding machine is pressed to the reinforcing bar S and a triggerlever 22 shown in FIG. 1 is pulled, the binding wire feed mechanism 4 isstarted to feed out the binding wire W to the upper side. As shown byFIG. 6, the binding wire W is formed in a loop shape along the nose 7,the front end is brought to between the center clamp plate 8 and theguide clamp plate 9 (depth side of paper face) of the binding wire clampmechanism 3 and impinges on a stopper portion 9 a provided at an upperend of the right clamp plate 9 to stop. The right clamp plate 9 isclosed by a cam mechanism and the front end of the binding wire isclamped by the center clamp plate 8 and the right clamp plate 9.

Successively, the binding wire W is pulled back by reversely driving torotate the main drive gear 13 having the V groove and the driven gear 14having the V groove of the binding wire feed mechanism 4, the feed motor15 is driven to rotate reversely up to a previously set rotationalnumber by the control portion and the binding wire W is wound around thereinforcing bar S as shown by FIG. 7. Further, after sufficientlypulling back the binging wire W to stop, the gears 13, 14 having the Vgrooves are reversely rotated until reaching a predetermined rotationalnumber, and the main drive gear 13 having the V groove and the drivengear 14 having the V groove are reversely rotated in an idly rotatedstate by slipping while pinching the binding wire W until the feed motor15 is stopped. That is, even when there is a difference in a diameter ofthe reinforcing bar, a difference of an amount of pulling back thebinding wire W can be absorbed by idly rotating the gears 13, 14 havingthe V grooves. In this way, by setting the reverse rotational number ofthe gears 13, 14 having the V grooves constant, the binding wire W canbe brought into close contact with the reinforcing bar S regardless of aboldness or a number of pieces of the reinforcing bars, a kind of thebinding wire, and an external condition of an outside air temperature orthe like, or a voltage of a battery.

Successively, after cutting the binding wire W by driving to rotate anouter side ring portion of the cutter devise 11, the left clamp plate 10is closed by the cam mechanism and the rear end of the binding wire isclamped by the center clamp plate 8 and the left clamp plate 10, a totalof the biding wire clamp mechanism 3 is driven to rotate and thereinforcing bar S is bound by twisting an end portion of the loop of thebinding wire W as shown by FIG. 8. Further, after finishing to bind thewire, the clamped end portion of the binding wire W is released toreturn to the initial state of FIG. 5. Further, with regard to thecontrol of the reverse rotational number of the main drive gear 13having the V groove, various detecting means of a pulse detectingcircuit of detecting the rotational number of the feed motor 15, arotational number sensor of directly detecting the rotational number ofthe main drive gear 13 having the V groove and the like are naturallyapplicable.

Further, in place of the constitution of setting the contact pressure ofthe main drive gear 13 having the V groove and the driven gear 14 havingthe V groove to permit to slip the binding wire W, as shown by FIG. 9,there may be constructed a constitution in which a torque limiter 24 ofa friction clutch or a ball clutch or the like is interposed between anoutput shaft of the reduction gear mechanism 16 and the gear 13 forfeeding, after completely pulling back the binding wire W, the maindrive gear 13 having the V groove and the driven gear 14 having the Vgroove are stopped by friction relative to the binding wire W, and onlythe feed motor 15 and the reduction gear mechanism 16 are rotated up tothe predetermined reverse rotational number.

Further, the invention is not limited to the above-described embodimentbut can variously modified further in the technical range of theinvention and the invention can naturally cover the modifications.

INDUSTRIAL APPLICABILITY

As has been explained above, according to the reinforcing bar bindingmachine of the invention, the binding wire feed mechanism is driven torotate reversely by the constant rotational number in the step ofpulling back the binding wire, when pulling back is finished beforefinishing the pulling back step, the drive system is reversely rotatedby slipping relative to the binding wire and therefore, the binding wirecan completely be pulled back regardless of the boldness or the numberof pieces of the reinforcing bars, the kind of the binding wire, theexternal condition, the voltage of the battery or the like and there isnot a concern of cutting the binding wire, which archives an effect instabilizing a binding function.

1. A reinforcing bar binding machine comprising: a binding wire feedmechanism for feeding out a binding wire so as to wind around areinforcing bar; a binding wire grasp mechanism for grasping andtwisting the winding wire wound around the reinforcing bar; a bindingwire pull back mechanism for pulling back a loop of the binding wirewound around the reinforcing bar to be brought into close contact withthe reinforcing bar and thereafter twisting the binding wire; controlmeans for reversely rotating a drive system of the binding wire feedmechanism by a predetermined rotational number in pulling back thebinding wire; and means for permitting to slip the drive system forrestricting a pull back tension exerted to the binding wire to be equalto or smaller than a limit value of cutting the binding wire.
 2. Thereinforcing bar binding machine according to claim 1, wherein thebinding wire feed mechanism comprises: a main drive sheave; and a drivensheave brought into elastic contact with the main drive sheave, and whena feed back tension exerted to the binding wire pinched between the pairof sheaves exceeds a certain value, the sheaves are idly rotated and thepull back tension exerted to the binding wire is restricted.
 3. Thereinforcing bar feeding machine according to claim 1, wherein thebinding wire feed mechanism comprises: a main drive sheave; and a drivensheave brought into elastic contact with the main drive sheave, thedrive system of the binding wire feed mechanism includes a torquelimiter, and when a pull back tension exerted to the binding wirepinched between the pair of grooves wheels exceeds a certain value, themain drive sheave and the driven sheave are stopped so as to restrictthe pull back tension exerted to the binding wire.
 4. The reinforcingbar binding machine according to claim 3, wherein the torque limiter isa friction clutch or a ball clutch.
 5. A reinforcing bar binding machinecomprising: a drive sheave; a driven sheave brought into elastic contactwith the drive sheave; and a motor that normally and reversely drivesthe drive sheave.
 6. The reinforcing bar binding machine according toclaim 5, further comprising: a lever to which the driven sheave isattached; and a spring attached to the lever, wherein the driven sheaveis brought into elastic contact with the drive sheave by a spring forceof the spring.
 7. The reinforcing bar binding machine according to claim5, wherein the motor normally drives the drive sheave so as to feed abinding wire, and reversely drives the drive sheave so as to pull backthe binding wire until reaching a predetermined rotational number.
 8. Areinforcing bar binding machine comprising: a drive sheave; a drivensheave in mesh with the drive sheave; a motor that normally andreversely drives the drive sheave; and a torque limiter disposed betweenthe motor and the drive sheave.
 9. The reinforcing bar binding machineaccording to claim 8, wherein the torque limiter comprises one of afriction clutch and a ball clutch.
 10. The reinforcing bar bindingmachine according to claim 8, wherein the motor normally drives thedrive sheave so as to feed a binding wire, and reversely drives thedrive sheave so as to pull back the binding wire until reaching apredetermined rotational number.